An image forming apparatus includes an image forming portion, a belt, an inner roller, an outer member, an inner roller position changing mechanism, an acquiring portion, and a controller. In a case that information acquired by the acquiring portion shows that first and second recording materials are coated paper, the controller controls a position changing mechanism so that a position of the inner roller when a toner image is transferred onto the second recording material is changed to a second position. In a case that the information acquired by the acquiring portion shows that the first and second recording materials are plain paper, the controller controls the position changing mechanism so that the position of the inner roller when the toner image is transferred onto the second recording material is maintained at a first position.

An intermediate transfer belt assembly includes an intermediate transfer belt, a driving roller, a backup roller, a driving frame; and a backup frame. The driving roller and the backup roller spaced apart from each other to support and move the intermediate transfer belt in a first direction. The driving frame is to rotatably support the driving roller. The backup frame is connected to the driving frame, is to rotatably support the backup roller and is to move in the first direction.

An image forming apparatus includes a photosensitive member, a charging member, an exposing unit, a developing member, an intermediary transfer member and a voltage applying portion. A controller controls a primary transfer contrast which is a difference between a transfer voltage applied by the voltage applying portion in a nip and a potential of a part exposed by the exposing unit on the photosensitive member. By applying the transfer voltage to the intermediary transfer member, the controller transfers the toner image from the photosensitive member to the intermediary transfer member by flowing a current in a circumferential direction. The controller controls the primary transfer contrast by controlling the transfer voltage based on information on a usage state of toner related to a number of printed sheets. The controller controls so that the transfer voltage becomes lower as the number of printed sheets is larger.

An image forming apparatus includes an image bearing member, a transfer member, an acquiring portion, an applying portion, and a controller. When a transfer voltage is subjected to constant-voltage control so that the transfer voltage applied to the transfer member by the applying portion is substantially constant, in a case that the transfer voltage, when a toner amount used for a toner image is a first toner amount, is a first voltage, the controller controls the applying portion so that the transfer voltage is a second voltage lower in absolute value than the first voltage in a case that the toner amount is a second toner amount greater than the first toner amount. The acquiring portion acquires toner amount information on the toner amount for each toner image transferred onto a single recording material.

An image forming apparatus includes an image bearing member, a transfer member, an acquiring portion, an applying portion, and a controller. When a transfer voltage is subjected to constant-voltage control so that the transfer voltage applied to the transfer member by the applying portion is substantially constant, in a case that the transfer voltage when a toner amount used for a toner image is a first toner amount is a first voltage, the controller controls the applying portion so that the transfer voltage is a second voltage smaller lower in absolute value than the first voltage in a case that the toner amount is a second toner amount ager greater than the first toner amount. The acquiring portion acquires toner amount information on the toner amount for each toner image transferred onto a single recording material.

An electroconductive roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The arithmetic mean peak curvature S.sub.pc of a surface of the surface layer is equal to or greater than 1,880 (1/mm), and is equal to or less than 14,024 (1/mm) The density of peaks S.sub.pd of the surface of the surface layer is equal to or greater than 93,406 (1/mm.sup.2), and is equal to or less than 151,476 (1/mm.sup.2). The surface area of the surface layer per unit projected area is equal to or greater than 1.255, and is equal to or less than 5.132.

An electroconductive roll includes a core member, a rubber base material disposed around the core member, and a surface layer disposed around the rubber base material. The arithmetic mean peak curvature S.sub.pc of a surface of the surface layer is equal to or greater than 1,880 (1/mm), and is equal to or less than 14,024 (1/mm) The density of peaks S.sub.pd of the surface of the surface layer is equal to or greater than 93,406 (1/mm.sup.2), and is equal to or less than 151,476 (1/mm.sup.2). The surface area of the surface layer per unit projected area is equal to or greater than 1.255, and is equal to or less than 5.132.

In one example, a device comprises an image transfer member, a platen to form a first nip with the image transfer member, a photo imaging plate to form a second nip with the image transfer member, and a controller to determine first information relating to a characteristic of the first nip, and to determine second information for use in adjusting a relative position of the photo imaging plate and the image transfer member on the basis of the first information.

In one example, a device comprises an image transfer member, a platen to form a first nip with the image transfer member, a photo imaging plate to form a second nip with the image transfer member, and a controller to determine first information relating to a characteristic of the first nip, and to determine second information for use in adjusting a relative position of the photo imaging plate and the image transfer member on the basis of the first information.

A control circuit executes voltage adjustment processing of adjusting a voltage output from a transfer power source so that ae current detected by a detection circuit becomes a predetermined current value. The voltage adjustment processing is executed before a toner image is transferred from at least one of a first image bearing member and a second image bearing member to an intermediate transfer belt. A processor determines whether the second transfer member is in a state of contact or is in a state of separation on the basis of behavior of the current detected by the detection circuit in a period in which the control circuit is executing the voltage adjustment processing.